The present disclosure relates to subject matter contained in priority Japanese Patent Application No. HEI 11-267001, filed Sep. 21, 1999.
1. Field of the Invention
The present invention relates to an electrode plate unit for a rechargeable battery and a manufacturing method of same.
2. Description of Related Art
Batteries are classified into primary batteries and secondary batteries or rechargeable batteries, and there are various configurations for each of these two types of battery. FIG. 17 shows a conventional battery module made by connecting a plurality of rechargeable batteries and coupling them together as one so as to obtain the necessary power. In this battery module, a plurality of cells 41 (41a to 41j) made of sealed alkaline rechargeable batteries as shown in FIG. 18 are arranged side by side, with the long lateral walls of their battery cases 42 adjacent each other. End plates 52 are arranged against the outside of the cells 41a and 41j at both ends, and the group of batteries and the two end plates 52 are bound together with binding bands 53 so as to couple the cells together as one piece.
For the cells 41, an electrode plate group 47, comprising positive electrode plates and negative electrode plates layered with intervening separators, thereby constituting elements for electromotive force, is accommodated in a battery case 42 together with a liquid electrolyte, and the open end of the battery case 42 is closed with a lid 46 provided with a safety vent 45. From the upper end at one side of the positive electrode plates forming the electrode plate group 47, leads 49 extend upward and are connected to a positive electrode terminal 43 above them, and similarly, from the upper end of the other side of the negative electrode plates, leads 49 extend upward and are connected to an negative electrode terminal 44 above them. The positive electrode terminal 43 and the negative electrode terminal 44 are attached to the lid 46.
The positive electrode terminals 43 and negative electrode terminals 44 of coupled neighboring cells 41 are connected by connection plates 51, thereby connecting all cells 41 in series. When the battery cases 42 are coupled, ribs 48, which protrude vertically from the long lateral walls of the battery cases 42, are abutted against each other, forming coolant passages running in the vertical direction along the long lateral walls of the battery cases 42 in the space between ribs 48. The cells 41a to 41j are cooled by flowing air through these coolant passages.
The leads 49 are integrated to the electrode plate group 47 by welding. For the welding of the leads, according to Japanese Laid-Open Patent Application 7-220715, for example, laser welding is used more favorably than resistance welding, because, in resistance welding, the welding defects are often formed by the generation of sparks caused by oxide films or other foreign substances that exist in the welding portion, and uniform welding cannot always be accomplished. Thus laser welding is more favorably applied, and specifically, leads are usually provided with through-holes, through which laser beams are passed, whereby these through-holes are closed with molten metal, and when the metal eventually cools down and sets, the leads are integrally welded together.
With the configuration for the cells 41 of this conventional battery module, leads 49 extend from a portion at the upper end on one side of the electrodes and are connected to the electrode terminals 43 and 44, and consequently, there were the problems that the internal resistance of the battery was large, because the average distance from the surface of the electrodes to the collector portions of the leads 49 was long, and that the power output was low, because the utilization rate of the electrode active material was low.
The inventors of the present application have proposed an electrode plate unit for a rechargeable battery, wherein collector plates are abutted on the entire surface of the opposite lateral ends of the group of electrode plates, with lateral edges of each of electrode plates being integrally welded to the collector plates. In connecting the lateral edges of the electrode plates to the collector plates, however, sufficient bond cannot be achieved in the case of employing a seam-welding method, with the result that power output of the battery is decreased, or the welding strength is low. On the other hand, if laser welding is used, it is difficult to accomplish secure bonding of electrode plates with the collector plates without causing any adverse effects to the electrode plates. Accordingly, there is the need for a method of bonding lateral edges of electrode plates with collector plates in a favorable condition.
In view of these problems of the prior art, it is an object of the present invention to provide an electrode plate unit for a rechargeable battery, in which one lateral edge of an electrode plate group is securely bonded to a collector plate, and to a manufacturing method thereof.
To achieve the above object, a battery according to one aspect of the present invention comprises an electrode plate unit, including:
a plurality of positive electrode plates and a plurality of negative electrode plates that are alternately stacked upon one another with intervening separators therebetween, thereby constituting a group of electrode plates, wherein lateral edges of the positive electrode plates protrude beyond the negative electrode plates on one side, and lateral edges of the negative electrode plates protrude beyond the group of positive electrode plates on the opposite side; and
a positive electrode collector plate and a negative electrode collector plate that are respectively bonded to said protruded lateral edges of the positive electrode plates and the negative electrode plates, wherein the positive electrode collector plate and the negative electrode collector plate are formed with protruded portions on a surface which is to be bonded to the lateral edges of the positive electrode plates and the negative electrode plates.
While novel features of the invention are set forth in the preceding, the invention, both as to organization and content, can be further understood and appreciated, along with other objects and features thereof, from the following detailed description and examples when taken in conjunction with the attached drawings.